Fawkes API  Fawkes Development Version
sdl_keeper.cpp
1 
2 /***************************************************************************
3  * sdl_keeper.cpp - utility to keep track of SDL initialization state
4  *
5  * Created: Mon Nov 05 14:34:36 2007
6  * Copyright 2007 Tim Niemueller [www.niemueller.de]
7  *
8  ****************************************************************************/
9 
10 /* This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License as published by
12  * the Free Software Foundation; either version 2 of the License, or
13  * (at your option) any later version. A runtime exception applies to
14  * this software (see LICENSE.GPL_WRE file mentioned below for details).
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19  * GNU Library General Public License for more details.
20  *
21  * Read the full text in the LICENSE.GPL_WRE file in the doc directory.
22  */
23 
24 #include <core/exception.h>
25 #include <core/threading/mutex.h>
26 #include <core/threading/mutex_locker.h>
27 #include <fvwidgets/sdl_keeper.h>
28 
29 #include <SDL.h>
30 
31 using namespace fawkes;
32 
33 namespace firevision {
34 
35 unsigned int SDLKeeper::_refcount = 0;
36 Mutex SDLKeeper::_mutex;
37 
38 /** @class SDLKeeper <fvwidgets/sdl_keeper.h>
39  * SDL Reference keeper.
40  *
41  * Use this keeper to initialize and quit the SDL library. As there may be many
42  * modules using the SDL a central place for reference counting is needed.
43  *
44  * @author Tim Niemueller
45  */
46 
47 /** Private inaccessible constructor. */
48 SDLKeeper::SDLKeeper()
49 {
50 }
51 
52 /** Init SDL.
53  * Keeps track of SDL_Init calls and only calls SDL_InitSubSystem on consecutive
54  * calls.
55  * @param flags Same flags as for SDL_Init
56  */
57 void
58 SDLKeeper::init(unsigned int flags)
59 {
60  MutexLocker lock(&_mutex);
61 
62  unsigned int alive_subsys = SDL_WasInit(SDL_INIT_EVERYTHING);
63  if ((alive_subsys & flags) != flags) {
64  // Subsystem has not been initialized, yet
65  if (_refcount == 0) {
66  if (SDL_Init(flags) != 0) {
67  throw Exception("SDL: initialization failed");
68  }
69  } else {
70  unsigned int still_to_init = ~alive_subsys & flags;
71  if (SDL_Init(still_to_init) != 0) {
72  throw Exception("SDL: initialization failed");
73  }
74  }
75  }
76 
77  ++_refcount;
78 }
79 
80 /** Conditionally quit SDL.
81  * Use this after you are done with the SDL. No subsystem will be closed after all
82  * users of SDL quit the usage. Then the whole SDL will be released at once.
83  */
84 void
85 SDLKeeper::quit() throw()
86 {
87  MutexLocker lock(&_mutex);
88 
89  if ((_refcount > 0) && (--_refcount == 0)) {
90  SDL_Quit();
91  }
92 }
93 
94 /** Force quit of SDL.
95  * This will quit the SDL no matter of the reference count. Use with extreme care.
96  */
97 void
98 SDLKeeper::force_quit()
99 {
100  MutexLocker lock(&_mutex);
101 
102  SDL_Quit();
103  _refcount = 0;
104 }
105 
106 } // end namespace firevision
Base class for exceptions in Fawkes.
Definition: exception.h:36
Mutex locking helper.
Definition: mutex_locker.h:34
Mutex mutual exclusion lock.
Definition: mutex.h:33
Fawkes library namespace.